BackgroundAt present, there is no effective treatment for premature ovarian failure (POF), and stem cell therapy is considered the most promising treatment. Human umbilical cord blood mesenchymal stem cells (hUC-MSCs) have shown good regenerative ability in a variety of diseases including POI, but the method and dosage of hUC-MSCs to treat POI are not clear. This study aims to explore the treatment options of hUC-MSCs for POF by comparing single injection and multiple injections of hUC-MSCs on the ovarian function repair of POF caused by chemotherapy drugs.MethodsFemale mice were injected intraperitoneally with 30 mg/kg of busulfan and 120 mg/kg of cyclophosphamide to induce POF. In the single hUC-MSCs injection group, 7 days after the mice were injected with cyclophosphamide and busulfan, hUC-MSCs were transplanted into these mice. In the multiple injection group, hUC-MSCs were transplanted 7 days, 14 days and 21 days after the mice were injected with cyclophosphamide and busulfan. We evaluated ovarian morphology, fertility, follicle stimulating hormone and estradiol concentration, and follicle count, evaluated POF model and cell transplantation. In addition, real-time PCR, immunohistochemistry, miRNA chip and mRNA chip are used to evaluate the effect of cell therapy.ResultsCompared with the POF group, the ovarian size and primordial follicle count in the hUC-MSC group were significantly improved, and the fertility was also significantly improved. Immunohistochemistry showed that compared with the POF group, the anti-Mullerian hormone and Ki-67 in the ovary of the hUC-MSC group increased significantly, and ovulation was significantly restored. Real-time PCR showed that the expression of follicle stimulating hormone receptor, inhibin and inhibin in the hUC-MSCs group was significantly restored compared with the POF group. The results of mRNA and miRNA chips also showed that hUC-MSC restored ovarian function at the gene level. long-term treatment effect shows that the multiple transplantation hUC-MSCs group is better than the single transplantation hUC-MSCs group. 60 days after the mice were injected with cyclophosphamide and busulfan, the organ coefficient of multiple transplantation of hUC-MSCs increased compared with the POF group, the number of primary follicles increased, and hormone secretion increased. ConclusionThe results show that multiple trasplantation of hUC-MSCs can promote the recovery of ovarian function in POF mice more than a single transplantation. This study provides a basis for the therapeutic dose and therapeutic effect of hUC-MSCs on POF.